The Separation of a Binary Water/Ethanol Solution via a Continuous Feed Distillation Column as a Function of Feed Stage Location and Reflux Ratio

The purpose of this study was to investigate the separation of a binary water/ethanol solution via a continuous feed distillation column as a function of feed stage location and reflux ratio. The column was initially run with the feed entering at the first stage under reflux ratios of 7.3 and 2.36. The composition of the distillate and liquid product were recorded and compared with theoretical results predicted by the McCabe-Thiele graphical method. In addition, the effect of feed stage location was examined by feeding into the fifth stage while at a reflux ratio of 7.3. It was found that the distillate composition was approximately 20 % (by weight) at a reflux ratio of 7.3, whereas this value dropped to 15 % when running at a reflux ratio of 2.36. Although a higher reflux ratio is desired to produce a higher concentration of ethanol in the distillate, it must be considered that a higher reboiler duty, and in turn a higher operating cost, is required to accomplish this. It was also observed that changing the feed location to the fifth stage resulted in a decreased ethanol concentration in the distillate. Finally, it was found that for the distillate compositions attained in this experiment, the McCabe-Thiele graphical method predicted significantly fewer stages than found in the laboratory column. This indicates that a high inefficiency exists in the stages of the column and these factors should be further investigated.